Old School Barrel Fit vs Modern Fit

I have a 1965 Colt 45 acp Kit Gun built by Shockey. Really like the pistol but hate shooting it. Barrel unlocked immediately and slide comes back too fast and the recoil was harsh with 3.4 BE 200 lswc. Bottom lugs should be bearing against slide stop minimum of 0.050” before the barrel can unlock from the slide lugs (in other words slide can travel 0.050” to the rear before barrel can drop.
So I pulled the barrel and had it laser micro welded. I welded/refit the hood and bottom barrel lugs.
Pics will show old lug (blued finish) and new weld material (shiny finish) when viewing the lug from the sides. I’m almost finished with it and hope to be shooting it soon.
Jon 

Thanks for showing us, it is nice to see how Smiths of the past worked and what they worked with.

Is this a mousetrap gun?

bmize1 wrote:Is this a mousetrap gun?

Yes sir.

Thanks Jon... you have a source for laser welding...would you be willing to share???

Jon, is the reason for laser welding because of heating the barrel or just more precise deposits? I would think a good tig welder could do a very good job also. They must use very small wire to weld with to deposit such small beads.
 Could you show a picture of his recoil spring plug?
 I think that would be less work to accurize than a Clark tuner.
 Nice work as always Jon.
Stan

This is an interesting thread. I have a Shockey mouse trap that I unknowingly purchased over the phone. I never got it to shoot, but it is a lovely pistol with a lot of character. I will have to dig out my barrel and see how it compares with yours, Jon.

Theoretically, are these older barrels still good and plenty accurate? Is the fitting the main issue? I've read that it takes quite a few rounds to wear out a 1911 barrel, but interested on a gunsmith's take on this.

So what exactly is a mouse trap gun?

The mousetrap was a helical spring and roller recoil spring plug.that rode along the barrel.  It worked, kinda, sorta, ish!

Here is a pic which was in a Shockey Deluxe.

Here's some photos of my Shockey setup:

Full semi circle contact in the slide lug now?

With pistol upright the top of the slide stop contact at 12 o’clock is what’s most important; that’s your lockup timing. Any contact to the rear is just what keeps slide, frame and barrel aligned.
Jon

Jon, I understand how the top of the slide stop and the lower lug contour affects timing. At least I believe I do. But I'm confused about your contact to the rear comment. Are you talking about the rear, or bottom of the lower lugs where they contact the back side of the slide stop? I'm trying to think this through (after a couple glasses of wine), the height of the lower lugs above the slide stop adjusts the amount of engagement of the barrel upper lugs and the slide lugs. The contour, angle, and length of contact between the slide stop and lower lugs affects the barrel engagement timing. Finally, the lower lugs contacting the back side of the slide stop points the barrel, like the rudder on a boat. Please correct me if I'm mistaken.

Several fitting areas on the barrel affect barrel consistency on lock up. Loose hood fit both rear and sides allows the barrel to rotate somewhat axially and horizontally sided to side rotating at the bushing. The rear of the bottom lug contact against the slide stop pin has some resistance against this movement; spring force from recoil spring pushes bottom lug rear against the pin. 
Minimal hood tolerances alleviate most if not all of this movement. The fit of the barrel between the hood and first upper barrel lug also resist this movement.
So it’s a marriage between all the lock up surfaces that determines whether the pistol is your friend or not. I’m a firm believer that a looser barrel fit can shoot excellent from a machine rest but not from hand. It will be unforgiving from hand requiring much more consistent gripping and follow through. A properly hard fit barrel typically shoots slightly vertical groups from machine rest but spot on from hand. It is also more forgiving and will have less felt recoil. Hard fit barrel also uses lighter recoil spring to function.
Timing is bottom lug bearing surface and link length related. It can unlock too soon, too late or just right. Most gunsmiths don’t properly fit barrel link. Typically sloppy and will cause other issues.
Hope this answers your questions.
Jon

Thanks so much, Jon. I have two more questions, if you don't mind. Obviously, the pin hole in the link must be made oval to allow the barrel to move rearward with the slide. Does this increase stress when the pin and link "slap" against each other to pull the barrel down out of engagement? Also, do you file a flat surface on the top of the slide stop pin? I apologize for all of the questions, but the more I learn about the inner workings of the 1911 the more fascinating it becomes.

Link hole does not need to be oval. Typically butchered when oval instead of using correct link length.
Marine Corps used to flatten slide stop so that they could add a new slide stop pin when the pistol loosened up. They used different thicknesses of slide stop measured at the flat. I have done it but typically do not use that method. It’s great when you have professional shooters shooting tons of ammunition. Allows longer barrel life and not having to weld and refit.
Jon

On my ball gun, I radiused the top of the pin when I rebarreled it long ago, so that I could tighten with a new pin as described.  But, after all these years, it has never needed that new tightening.  I kind of don't expect to ever have to now that I'm not even shooting it as much.

Jon, Did you add some material to the front of the feet of the lug?  Was that to center the barrel pin hole so you could get away from enlarging the slide stop pin hole an overabundant amount?  Wouldn't that also change the position of the slide a bit rearward on the frame?  Or, am I way off base and missing everything by a mile?

Ed,
I added material mostly for esthetics and a little bit because I needed more flat bearing surface for longer lockup. In reality the barrel rides the link up to the point of just before the radius where the slide stop will start engaging the lockup flat bearing surface. I think back in the day longer links were hard to come by and they were typically too short which lead to egg shaping the larger link hole. Barrel link has two jobs; unlocking/pulling barrel down out of battery and barrel rides it until just before the start of lockup (engaging bottom lug flat). 
Slide position on frame is controlled by the rear of the slide stop pin where the bottom lug engages at 3 or 6 o'clock depending on your clock.
Hope this is understandable.
Jon

Jon Eulette wrote:Ed,
I added material mostly for esthetics and a little bit because I needed more flat bearing surface for longer lockup. In reality the barrel rides the link up to the point of just before the radius where the slide stop will start engaging the lockup flat bearing surface. I think back in the day longer links were hard to come by and they were typically too short which lead to egg shaping the larger link hole. Barrel link has two jobs; unlocking/pulling barrel down out of battery and barrel rides it until just before the start of lockup (engaging bottom lug flat). 
Slide position on frame is controlled by the rear of the slide stop pin where the bottom lug engages at 3 or 6 o'clock depending on your clock.
Hope this is understandable.
Jon

Thanks Jon,

All of that was what I understood, except that I didn't consider that the slide stop pin could be reduced where it contacted the lug feet (3/6 o'clock) to move the slide forward when in battery.  It had looked like you added material to that point on the lugs as well.  I "think" I understand all the timing details, but I do pick up more gunsmith "secrets" from time to time, and refine those I think I already know.

Ed,
The bottom barrel lug is cut for slide/frame alignment, not the slide stop pin.
Jon

Jon Eulette wrote:Ed,
The bottom barrel lug is cut for slide/frame alignment, not the slide stop pin.
Jon

That was my original understanding.

Jon Eulette wrote:. . .
Slide position on frame is controlled by the rear of the slide stop pin where the bottom lug engages at 3 or 6 o'clock depending on your clock.
. . .
Jon

This is what gave me the idea that reducing the radius of the pin at that contact point would also move the slide forward.

Oooopsy, 3 or 9 o’clock. Not 6.
Yes you could modify the slide stop pin. Shear strength of the slide stop pin would still be greater than the rear of the bottom lugs; approximately 0.100” vs 0.200”.
The mods to the slide stop can affect link contact points.
Jon

I didn't even notice the 6 vs. 9 error.

I see the point of certain pin modifications also affecting the link interfacing.  That pin has a lot of responsibility both in locking and unlocking!